I think it is American exceptionalism itself, as our official national ideology, that is now dangerous to our national interest in a way it has not been in the past. The reason for this is simple. During much of the 20th century, much of the world (outside of Latin America, that is, where we were always viewed as the empire) concurred with America's image of itself. Perhaps that was because of what we represented; perhaps, to take the realist approach you and I both favor, it was because it was in Europe's and much of East Asia's interest to do so. But at the very least, the sense we had of ourselves did not seem illegitimate to much of the world as it does now. But now is now, and we are still proceeding as if we get a kind of moral free pass no matter what we do, that we are exceptional.